Methods and systems for subsea direct current power distribution

Abstract

A subsea power distribution module includes an outer vessel defining an interior chamber and a plurality of power modules disposed within the interior chamber. The outer vessel is configured to maintain a pressure within the interior chamber substantially the same as an ambient pressure outside the outer vessel. Each power module includes a pressure vessel defining an interior chamber and a power converter disposed within the interior chamber of the pressure vessel. Each pressure vessel is configured to maintain a substantially constant pressure within the interior chamber of the pressure vessel.

What is claimed is: 
     
       1. A subsea power distribution module for use in a direct current (DC) power system, said subsea power distribution module comprising:
 an outer vessel defining an interior chamber, said outer vessel configured to maintain a pressure within the interior chamber substantially the same as an ambient pressure outside said outer vessel; and 
 a plurality of power modules disposed within the interior chamber of said outer vessel, each power module comprising: 
 a pressure vessel defining an interior chamber and configured to maintain a substantially constant pressure within the interior chamber of said pressure vessel independent of the pressure within the interior chamber of said outer vessel; and 
 a power converter disposed within the interior chamber of said pressure vessel. 
 
     
     
       2. The subsea power distribution module in accordance with  claim 1  further comprising:
 an interface for receiving an input DC power; and 
 a switchyard module disposed within the interior chamber of said outer vessel and coupled to said plurality of power modules, said switchyard module configured for selective coupling of said plurality of power modules to each other and to the interface. 
 
     
     
       3. The subsea power distribution module in accordance with  claim 1 , wherein said power converter comprises one of a DC to alternating current power converter and a DC to DC power converter. 
     
     
       4. The subsea power distribution module in accordance with  claim 1  further comprising an oil that substantially fills the interior chamber of said outer vessel. 
     
     
       5. The subsea power distribution module in accordance with  claim 4 , wherein each said power module is configured to transfer heat generated within the interior chamber of said pressure vessel to said oil in the interior chamber of said outer vessel. 
     
     
       6. The subsea power distribution module in accordance with  claim 1 , wherein said pressure vessel is configured to maintain a substantially constant pressure of about 100 kilopascals within the interior chamber of said pressure vessel. 
     
     
       7. The subsea power distribution module in accordance with  claim 1 , wherein said outer vessel further comprises:
 an interface configured for wet mateable connection to a DC power source without a differential pressure barrier; and 
 an output configured for wet mateable connection to a load. 
 
     
     
       8. A subsea power distribution system for providing alternating current (AC) power to at least one load located underwater, said system comprising:
 a subsea power distribution module configured to receive a direct current (DC) power input and provide AC power to a load, said subsea power distribution module comprising: 
 an outer vessel defining an interior chamber, said outer vessel configured to maintain a pressure within the interior chamber substantially the same as an ambient pressure outside said outer vessel; and 
 a plurality of power modules disposed within the interior chamber of said outer vessel, each power module comprising: 
 a pressure vessel defining an interior chamber and configured to maintain a substantially constant pressure within the interior chamber of said pressure vessel independent of the pressure within the interior chamber of said outer vessel; and 
 a power converter disposed within the interior chamber of said pressure vessel. 
 
     
     
       9. The subsea power distribution system in accordance with  claim 8 , wherein said outer vessel further comprises:
 an interface configured for wet mateable connection to a DC power source; and 
 an output configured for wet mateable connection to the load. 
 
     
     
       10. The subsea power distribution system in accordance with  claim 8 , wherein the load comprises an electric motor for driving a fluid pump. 
     
     
       11. The subsea power distribution system in accordance with  claim 8 , wherein each subsea distribution module further comprises:
 an interface for receiving an input DC power; and 
 a switchyard module disposed within the interior chamber of said outer vessel and coupled to said plurality of power modules, said switchyard module configured for selective coupling of said plurality of power modules to each other and to the interface. 
 
     
     
       12. The subsea power distribution system in accordance with  claim 8 , wherein said power converter comprises at least one of a DC to AC power converter and a DC to DC power converter. 
     
     
       13. A subsea power distribution system for providing alternating current (AC) power to a plurality of loads located underwater, said system comprising:
 a plurality of subsea power distribution modules configured to receive a direct current (DC) power input from a DC source, each subsea power distribution module configured to receive the DC power input and provide AC power to a different load of the plurality of loads, each subsea power distribution module comprises: 
 an outer vessel defining an interior chamber, said outer vessel configured to maintain a pressure within the interior chamber substantially the same as an ambient pressure outside said outer vessel; 
 a plurality of pressure vessels each defining an interior chamber and each disposed within the interior chamber of said outer vessel, wherein each said pressure vessel is configured to maintain a substantially constant pressure within the interior chamber of said pressure vessel independent of the pressure within the interior chamber of the outer vessel; and 
 a plurality of power components disposed within the respective interior chambers of said plurality of pressure vessels, said plurality of power components configured to receive the DC power input and output AC power to said module's load. 
 
     
     
       14. The subsea power distribution system in accordance with  claim 13 , wherein said plurality of subsea power distribution modules are electrically coupled together in series. 
     
     
       15. The subsea power distribution system in accordance with  claim 13 , wherein each subsea distribution module further comprises:
 an interface for receiving the DC power input; and 
 a switchyard module disposed within the interior chamber of said outer vessel and configured for selective coupling of said plurality of power components to each other and to the interface. 
 
     
     
       16. The subsea power distribution system in accordance with  claim 13 , wherein said plurality of components comprises a plurality of DC to AC power converters. 
     
     
       17. The subsea power distribution system in accordance with  claim 16 , wherein each DC to AC power converter of said plurality DC to AC power converters is disposed within the interior chamber of a different one of said plurality of pressure vessels. 
     
     
       18. The subsea power distribution system in accordance with  claim 17 , wherein each said pressure vessel is configured to maintain a substantially constant pressure of about 100 kilopascals within the interior chamber of said pressure vessel. 
     
     
       19. The subsea power distribution system in accordance with  claim 13 , wherein each subsea distribution module is coupled to the DC source via a single wet mateable DC connector without a differential pressure barrier, and each subsea distribution module is coupled to its load via a single wet mateable AC connector.